The present invention relates to two stage rivets which are used to releasably secure two parts together.
Two stage rivets are commonly used to secure or fasten parts to an automobile's framework. These rivets include a grommet which includes a head having a central hole and a plurality of rearwardly projecting legs which have an inwardly projecting catch at the end thereof. The rivet also includes a headed pin which has an enlarged central portion having an annular groove, recesses on either side of this central portion and a bulbous end. The pin is inserted into the central hole of the grommet and becomes located at a first position (the first stage) by the interconnection of these latches and the recess between the bulbous end and the enlarged central portion. In this condition the fastener can be inserted into a hole defined in two panels which are to be laminated. Once inserted, the pin is pushed further into the grommet until the head of the pin becomes flush with the head of the grommet.
At this second position (the second stage of the rivet) the latches on the legs are located in the annular groove of the enlarged central portion thereby forcing the forward ends of the legs outwardly forcefully clamping the laminated panels between the head of the grommet and the bent legs.
When the rivet is to be released the pin can be pushed in further (third stage) until the latches locate in the recess adjacent the head. The legs reassume their initial shape thereby allowing removal of the rivet.
Since the rivet is plastic the legs should return to their original position whenever the rivet is positioned at the first or third stages. But such return displacement is not instantaneous and as a result the pin can be separated from the grommet and this is very undesirable.